Rubber half sole



April 7, 1925.

C. R. KEISER RUBBER HALF soLE Fld NOV. 17. 1925 abbot nu;

Patented Apr. 7, 1925.

UNITED STATES PATENT oFFicE.

CHARLES It. KEISELR, F AUBURN, INDIANA, ASSIGNOR T0 THE REGAL RUBBER C0.,

OF DAYTON, O'HIO.

RUBBER HALF SOLE.

Application led November 17, 1923. Serial No. 675,387.

To all whom it may concern.'

Be it known that I, CHARLES R. KEISER, a citizen of the United States, residing at Auburn, in the county of De Kalb and State of Indiana, have invented new and useful Improvements in Rubber Half Soles, of which the following is a specification.

`The invention relates to rubber soles for half soling worn shoes or new shoes when extra protection is desired.

Rubber soles which have been heretofore used have been of such structure that it has been necessar to have the soles attached by a skilled cob ler or manufacturer of foot-` wear.

been entirely satisfactory or successful because the rubber sole being fastened to the leather sole only at particular points and around the outer edge and not vuniformly over the entire surface of the sole, a greater strain is placed upon these points where the fastening or attachment to the leather sole is made thanl the rubber can withstand, thereby causing the rubber to break away from the stitching, nails or fasteners and ruiningthe usefulness of the sole.

The object of the present invention is to improve the construction of rubber soles and to provide a simple practical and eiicient rubber sole of strong and durable construction and increased wearing qualities, which will require no stitches, nails or other metallic fasteners and which will not be secured in separate pointsonly, but attached to the leather sole uniformly throughout the entire area of its upper surface.

A further object of the invention is to provide a rubber sole of this Character adapted to be a plied to the leather sole of a new or` old s oe without removing any of the lay- 5 ers of the original leathesole, thereby enabling theleather sole to insulate the rubber half-sole from the feet and prevent discomfort to the wearer, particularly preventing what is generally termed drawing of the rubber or drawing of the feet.

Another object of the inventita is to afford a neat, servicable, satisfactory and economical method of half soling shoes and of enabling the; half soles to be applied by either an experienced workman or anineX'-l perienced person.

A further object of the invention is to rovide a rubber half sole which will be p-hant and elastic and adapted to elongate and adjust within itself, the strains put upon it by a person in the act of walking, thereby relieving the strains at the point of attachment or union of the rubber sole with the leather sole.

With these and other objectsfin view, the invention consists in the construction and novel' combination and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings and pointed out in the claims hereto appended, it being understood that Various changes in the form, proportion and minor details of construction, within the scope of the claims, may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings, in which like characters of reference designate corresponding parts in the several views:

Figure 1 is a reverse plan view of a portion of a shoe provided with a rubber half sole constructed in accordance with this invention. Figure 2 is an edge view of the rubbersole showing the layers before vulcanization.

Figure 3 is a similar view illustrating thel layers pf the rubber half sole after vulcanization.

The rubber half sole of the resent invention comprises a lower or trea. layer 1, and intermediate and upper layers 2 and 3 of a thickness less than the thickness of the bottom or tread layer which is subjected to the wear of the shoe. The tread layer l con-v sists of rubber or a rubbercompound, contains vulcanizing agents of the well known character such as sulphur, etc. On the tread layer 1, is laid one or more of the layers 2 and 3 of rubber of the-proper thickness or rubber compound and these layers 2 and 3 do not contain any vulcanizing agents. The sole thus constructed is placed in a mold and subjected to heat. vThe layers of rubber .and rubber compound 2 and 3 are of such nature as to prevent vulcanization from tak? ing place throughout the entire thickness of the sole and are designed to be of such a thickness as to leave the upper or outer surface of the top layer 3 unvulcanized, the vulcanization extending throughout the tread layer and suiiciently through the intermediate layer and into the lower portion of the top layer to unite the layers and form a unitary structure. It is preferred to have the top layer of pure vrubber and not compounded rubber.

It is very important thatthe proper thickness ofthe layers of rubber without vulcanizing agents be maintained'because vulcanization is a chemical reaction and during this reaction, there is a certain -amount of diffusion within a vulcanizing stock itself and rubber stock placed in contact with it. It is due to this diffusion that the rubber layers without vulcanizing agents are vulcanized or partially vulcanized. The extent of this diffusion or migration of sulphur is limited by the nature of the compound and by the factl that rubber placed under vulcanizing heat will notbecome a liquid and this limit-ed diffusion in turn, limits the extent of the vulcanization in the rubber containing no vulcanizing agents.l It is therefore, necessary that the proper thickness of the rubber containing no vulcanizing agents be such that diffusion and vulcanization take place beyond the points of union but not -to the up er or outer surface of the top layer of rubber containing no vulcanizing agents. ,n

Heretofore, rubber soles composed of a combination of various layers have been vulcanized together, the layers having each a vulcanizing agent in its composition.y The methods heretofore in use have permitted a vulcanization to. take place throughout the entire mass. This would defeat the object of the present invention, in which the upper surface and substantially the upper half of the top layer is left unvulcanized. In Figure 2 of the drawing, the layers are indicated plain to illustrate the sole before vulcanization and in Figure 3, the layers are shown after vulcanization of the tread. The tread layer which is illustratedl darker than the intermediate layer shows complete'vulcanization of the tread part of the half sole.

The dotted portions show partial vulcanization as having taken place due to the vulcanizing agents in the lower tread layer and that partial vulcanization has passed beyond the lines separating the layers having no yulcanizing agents from the tread layer havmg vulcanizing agents. The top surface and unvulcanized top portion of the uppermost layer is indicated above the dotted portion by a plain or white section or portion;

The attachment of the rubber half sole thus formed to a leather sole is accomplished by roughenlng the-leather sole with a sharp lnstrument and applying several coats of rubber cement to the leather soley and a coating of cement to the rubber sole to freshen the latter and as soon as both are dry, they are united by pressure with the hands. In Figure 1, the rubber sole is attached to the leather sole 4 of a shoe. The leather sole 4 preferably extends beyond the edges of the rubber sole, the latter being designed to be somewhat smaller in length and breadth than the leather sole to which it is applied so that the rubber sole will not be seen and the shoe will maintain substantially its natural appearance when on the foot. This also enables the outer edge of the leather sole to be polished.

Adhesion of the two layers of cement isY obtained by pressing the soles together as above stated and this also causes the soft unvulcanized rubber to fill andbecome firmly embedded in the uneven surf-ace of the leather sole, all the air being excluded from between the rubber sole and the leather sole and prevented from entering by a perfect union of the two soles. 'The rubber sole is held firmly to the leather` sole by adhesion and by atmospheric pressure.` The present invention does not attempt to have the tread of the rubber sole possess the same physical characteristics as the leather sole, but instead, as above stated, the rubber tread is pliable and elastic and treads of this character will outwear leather soles several times their thickness. The plurality of layers of rubber, as indicated in Figure 3 of the drawing possess different characteristics and due to the complete and partialv vulcanization are of different compos1tion and properties, and each serves a particular purpose in the v present invention.

The merits of the invention may be summarized as follows: v

First, an economical rubber half sole so easily attached hat no skill is required in making a permanent attachment, and at the same time greatly prolonging the wearing surface of shoes.

Second', a.' soft pliable sole tread which will readily conform to the ground so :as to prevent slipping.

Third, a half solo that is water proof and docs not detract from the neatness of the shoe.4

The vulcanizing of a mixture of rubber stocks together, one of which does not vulcanizc on its outer surface, will cause difficulty such as the adherence of the raw stock to the mold or to any covering that may be placed between the raw stock and the mold, thereby making it impossible to properly separate from the mold or covering. This is due to the fact that practically all rubber is milled and calandered into sheets before vulcanizing and thereby materially softened.

The present invention has obviated this'diiiculty by not ca-lauderng or milling the raw rubber', but by using that part of hisxubber in a crpe form just as it comes from the plan-tation.

Rubber in crpe form is thin sheets of raw rubber having a rough surface and marketed under various trade names as Thin first latex crpe and Clean thin brown crpe.

What is claimed is:

l. A partially vulcanized `rubber half sole comprising a plurality of layers of rubber having latex arranged to control the migration of sulphur, the vulcanization extending from the bottom of the half sole and terminating short of the top of the half sole, leaving the up-per surface of the half sole unvulcanized whereby a uniform adhesion and firm attachment between all parts of the entire surface of the rubber half sole and a leather sole may be obtained by an adhesive 'air completely excluded.

2. A' partially vulcanized rubber half sole comprising a plurality of layers of rubber, one of the layers of rubber having a vulcanizing agent incorporated in it and the Sole being vulcanized, and having latex controlling the migration of sulphur, the vulcanization uniting the layers and extending through the bottom layer and terminating short .of the upper surface of the top layer,

the upper surface and adjacent portions of the top layer being unvulcanized, so that a uniform adhesion and rm attachment between all parts of the entire surface of the rubber half sole and the leather sole may be obtained by an adhesive and air entirely excluded from between the rubber half sole and the leather sole. Y

3.- A partially vulcanized rubber half sole comprising a bottom tread Section having a vulcanizing agent incorporated in it, and a plurality of layers containing no vulcanizing agent including latex for controlling thc migration of sulphur, the sole being vulcanized and the vulcanizing agent of the tread layer extending from the bottom layer beyond into the top layer and terminating short of the upper surface thereof, the layers being united by the vulcanization and the upper surface and adjacent portions of the top layer being unvu1- canized to permit a uniform adhesion and firm attachment between all parts of the entire upper surface of the rubber half sole and the leather sole and air to be completely excluded from between the rubber half sole 'and the leather sole.

In ltestimony whereof I have hereunto set my hand.

CHARLES R. KEISER. 

